This invention relates to a method of producing extracellular products from aerobic microorganisms. In particular, it relates to a method wherein an aerobic microorganism is grown in an aqueous medium on one side of an oxygen-permeable surface while the opposite side of the surface is contacted with oxygen, and an extracellular product is harvested from the aqueous medium.
Lignin is the major non-carbohydrate constituent of wood and woody plants and functions as a natural plastic binder for cellulose fibers. Organisms, such as fungi, that feed on cellulose produce a peroxidase called "lignin peroxidase" which attacks and degrades lignin, thereby giving the organism access to the cellulose. Peroxidases, in general, are enzymes that utilize hydrogen peroxide as a co-substrate in reactions that involve one electron transfer and are useful in a variety of chemical processes, including catalysis reactions in the production of pharmaceuticals, enzyme catalyzed analytical reactions, and the degradation of toxic organic waste products. At the present time, peroxidase can be obtained from horseradish or from fungi that naturally produce it. Most processes for obtaining lignin peroxidase from fungi involved agitation in a large reactor with a growth medium and it has been shown (see Venkatadri, R. and Irvine, R. L., "Effect of Agitation on Ligninase Activity and Ligninase Production by Phanerochaete chrysosporium, " Applied and Environmental Microbiology, 56, 2684-2691, 1990) that the presence of a surfactant is required to prevent the agitation from inactivating the enzyme. The current method of obtaining lignin peroxidase is costly and, as a result, the price of lignin peroxidase is relatively high.